Anisotropic resistivity effects on the minimum dissipation states of tokamak plasmas sustained by coaxial helicity injection

The minimum dissipation states of a tokamak-like plasma sustained by helicity injection are determined. The Ohmic energy dissipation rate is minimized using the helicity balance as a constraint and considering different resistivity values in the directions parallel and perpendicular to the magnetic field inside the plasma. The resulting Euler-Lagrange equations are solved, assuming axial symmetry, for different values of the ratio between the parallel and perpendicular resistivities (eta (parallel to)/eta (perpendicular to)) It is shown that previously published results are not completely correct and that the radial profile of mu (0)j(phi)/B-phi, (the ratio between the toroidal current density and the toroidal magnetic field) changes significantly when eta (parallel to)/eta (perpendicular to) decreases.